Leaf crops grow in polytunnels on the roof of the old mill – home to the Biospheric Project. Photograph: Christopher Thomond

Manchester international festival prides itself on finding interesting venues. Hence Kenneth Branagh doing Macbeth in a deconsecrated church down the Ancoats end of the Northern Quarter, and Massive Attack soundtracking an Adam Curtis film live in an old railway depot near Piccadilly.

But perhaps the most unlikely one this year is over the border in Salford, in an old mill by the River Irwell. Renamed the Biospheric Project, the three-floor space has been transformed into an urban farm and hi-tech research laboratory, which has the ambitious long-term aim of feeding the surrounding Blackfriars estate and – according to the project's 34-year-old director, Vincent Walsh – luring the locals away from the 67 unhealthy take-away joints he claims lie within a two-mile radius of the area.

"It's not going to happen overnight," concedes Walsh, a PhD student who has tattooed knuckles and dreadlocks approaching his waist. "But this is the start of a 10-year project base in an area of urban deprivation where it is really needed, on an estate where access to healthy food is so poor."

From the outside, the building doesn't look very different from the other red-brick industrial spaces crumbling all around Greater Manchester. But opposite, what was until a few months ago a piece of wasteland now houses a fledgling orchard of 70 fruit trees, a raised bed containing green plants such as Good King Henry (the UK's answer to spinach) and a vermiculture system (essentially: a worm farm containing 100,000 writhing worms) as well as an abandoned bath tub. The worms, says Walsh, are a crucial part of the creation of a diverse ecosystem and an important bonding tool for the local community: "We sell them to the local fishermen for a good price and in return they give us their compost." Remarkably, given the Irwell's reputation for scum and pollution, the river is home to the world's oldest angling club, the Salford Friendly Anglers Society (est 1817).

Head inside the mill on one of the festival's public tours and a whole new world opens up. There are tanks of fish where academics are farming tilapia and carp, jazzy window boxes and two clever aquaponics systems. These hi-tech inventions use nitrate-rich water from the fishtanks to fertilise salad and herb crops. One of the systems pumps water from fishtanks on the first floor to grow leaf crops in rooftop polytunnels, next to the hen houses. The second is what Walsh calls a "greenius wall" – a thin greenhouse growing salad designed to replace a normal exterior wall, designed to maximise bio-productivity by using dormant space on the sides of buildings.

This isn't just a hippy utopian project, but a thriving research centre, funded by the likes of Siemens and architects BDP – both of whom see commercial potential in the experiments. Urban Splash, the regeneration company that has changed the face of modern Manchester with its hip warehouse conversions, is another supporter. Tom Bloxham, chairman of Urban Splash and of MIF, is on Walsh's PhD supervisory team. He is full of admiration for Walsh's can-do spirit. "So many people find reasons not to do things, don't they?" he says. "Vinnie is asking very important questions about urban food production and distribution and has come up with really interesting ideas, which may develop into commercially viable propositions in time." The Biospheric Project won't put the nearest Aldi out of business. But what is it they say? From small acorns oak trees grow.

Urban Splash owns the mill ("an opportunistic purchase," admits Bloxham) but has rented it to Walsh for a peppercorn rent. For the first two years, Walsh lived inside the semi-derelict building, sleeping on sandbags and surviving without electricity and running water during the early days.

A few weeks ago, the Biospheric Project opened up a wholefood shop called 78 Steps below one of the nearby towerblocks. Named for its proximity to the mill, the idea is that the shop will eventually sell produce grown in the Biosphere round the corner. For now, though, the shop is sourcing much of its fruit and vegetables from the same source as the Unicorn organic grocery in the upmarket south Manchester suburb of Chorlton, new home to many of the BBC's relocated staff.

"Why shouldn't people round here have access to good, healthy food?" asks Steve Coles, a local resident who has just been taken on as the shop's manager. "We will eventually have a better offering than Chorlton, because people here can get involved right from the start."

So far the shop is proving a hit. Zamzam Mohammed, 16, said her mum had been in and was impressed by the quality and prices – £1 for a kilo of bananas, sweet potatoes for a very reasonable £1.22/kg. "It's really good, we'll have more fresh food, it's more organic."

Sam Highfield, 27, a BBC visual-effect specialist who has shunned Chorlton for Blackfriars, says, " You wouldn't expect an organic store to be in a place like this, they're normally more suited to middle-class areas. It has a lot of stuff that the two convenience stores don't." Even the local competition gives 78 Steps a ringing endorsement. "The shop-owners have promised us that they won't put the same food in their store; they're just selling fruit and veg, which we don't have," says Rubi Shaheen, 37, behind the counter at Papa's Mini Mart. "I think it's really good for the poorer people around here." Other locals say they've enjoyed seeing the project develop. "I've loved watching them put it all together from my flat; it's been really interesting, though I'm not exactly sure what they're doing," says Susan Sajid, 52, who works in a Salford bookmaker. "But the project has to be a good thing. I don't know whether they'll be able to keep the shop going, but I hope they do."